Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies

Intake of total protein was associated with a lower risk of all-cause mortality (pooled effect size 0.94, 95% CI 0.89 to 0.99, P<0.001), as was intake of plant protein (0.92, 0.87-0.97, P=0.003), which was also associated with reduced CV mortality (0.88, 0.80-0.96, P=0.001).

SPS commentary:

The authors note that the observed inverse associations between plant protein intake and mortality from all causes and CV disease remained significant in studies that controlled for energy, BMI, and macronutrient intake, and in studies that applies a food frequency questionnaire for dietary assessment.

They discuss previous research showing reduction in processed meat intake was associated with a small reduction in cancer mortality, and suggest the lack of association in their review could be due to combining protein from different animal sources; also the different associations of animal meat and animal protein intake (with mortality explained by the fact content of meat, for example). Different methods used in the processing and cooking of meats could also explain the discrepancy.

The authors conclude that their findings support current dietary recommendations to increase consumption of plant proteins in the general population, with an additional 3% of energy from plant proteins a day associated with a 5% lower risk of death from all causes.

British Medical Journal